<html>
  <body>
    页面跳转后再调用 fetch
    <script>
      window.location.href = 'https://baidu.com'
      // setTimeout(() => fetch('//lo:3000/ping'));
      alert(123)
      setTimeout(() => {
        var xhr = new XMLHttpRequest();
        xhr.open('GET', '//lo:3000/ping',);
        xr.send();
      },255)
    </script>
  </body>
</html>